Propeller drive



June 29, 1948.

PROPELLER- DRIVE Filed Deo. 14, 1944 Jf. S. HASBROUCK 7 Sheets-Sheet 1 ATTO RNEY June 29, 194s.

J. HASBROUCK PROPELLER DRIVE '7 Sheets-Sheet 2 Filed nec, '14, 1944 June 29, 1948. J. s. HAsBRoUcK 2,444,227

y PROPELLER DRIVE l Filed Dec. 14, 1944 7 sheets-sheet ATTORNEY June 29, 194s.

J.S.HASBROUCK PROPELLER DRIVE `,7 Sheets-Sheet 4 Filed Dec. 14, 1944 www Q ATTORNEY June 29, `194s. J, s HASBRQUCK 2,444,227

PROPELLER DRIVE Filed Dec. 14, 1944- 7 Sheets-Sheet 5 INVENTOR MM .fw

ATTORNEY June 29, 1948. m J, s. HASBROUCK 2,444,227

` PROPELLER DRIVE Filed Dec. 14, 1944 '7 Sheets-fSheet 6 BMKM ATTORNEY June 29, 1948. J. s. HAsBRoucK A 2,444,227

' i PROPELLR bRIvE I Find Dec. 14,- 1944 7 rfsheets-sheet fr INVENTOR ATTORNEY Patented June 29, 1948 n einem;

rnoPrLLER nave: .telnrA Stephens-Hasbrouek, Glastonbury Conn.,

assig-norr tov Unitedg Aircraft. Corporation; East.: Hartford,- V Qonnm ahcorporation ot, Delaware Application Decemberflll, 1944', SerialtN. 568,108

` SAGlaimss.` (Cl. 14e-371) l Thisvinvention., relates:` to.` aircratt propeller: reslientlylfrom one. operativey or drivingposition.` drives and particularly tesa Irmitispeedtransmisto another and with a snap action in either-direc# sion betweenthe-enginermainshaftandi t'heproition. l

panel@ Shaft. andi. means; for Ghanginglthef speed. Another object of t-he invention istojhydranli'-` ratio -otltheftransmission 5;; cal-ly` actuate the speedl changing` device, the

The-invention relatesmore speci'cally. to means.; hydraulic connections forthis Vpurposealso` acting.

for?eiectingfchangesin the speed ratio.loetvifeen:ane\v 170 Pesetthe engine governoraircraftengine-main shaftand thepropeller shaft Further objects are to .provdelan imDIOVed syn` driven thereby se that a-change-in the Tspeediot. chromesh mechanism for-a multi-speedpropell'er therpropeller'relative to that otitheengineimay be 1.0; reductionl gear andi 13D-f prevent oVelSpeedIlg Gf efte'ctedrquickly by power actua-tedsmeansiduringt thev engine during.` the .gear shifting operation;

the `cor-itinuing rotationof v the.: engine and; prior.. Other yobjects andi advantageswillbe apparent pellen.. from the speoication..andclaims andifrom the In\- certainA types; ot modernaa-irplanesl having; drawings'.whichillustrateA what, snow considered.

high; rnzmimum.-rsneefils;` and;` relative hea-vv: Wing: 15;. to be a. preferredA embodlmentmthe invention..

loadings-g. it has vbeen! fourni: desirable tozpxolvide.. In: the. drawings,`

means forichanging thefgeanratiobetween theene l Fig'. Lis.atlongitudinalisectional viewtoifa speedf gine and; the; propeller;` Elonv example; im some changing mechanism illustratingthe present ininstaliations it;mayrloezfeuncl` desirableito op@rate Vention, thesectnbeng taken. substantially- 0n the propeller: at avery high. rotational speedland.; 20: the planeszof broken line `l-lfin.1Fieu2.

Withtheblades adjustedzgctor relatively low pitch; Fig. 21' is:V a-transverse sectional View of the:Y angle `dining take-oft in, orderf to develop` the mechanismshown. imFig'. 1,v the sectionnb'eing.

necessary f tractive: thrustv Whilel the, airplane is; taken on the planes of broken line Ze-f-Zfin` Fig; 1., travelling-at relativelyvslow speeds. AstheSlllfd-t` Eig, 3 is: a. longitudinalzelevation insectiorr. of

of' the airplane increases it is desirable'tozoperate; the shifting.memberrandadjacent partsconnelcted;

the propeller at, a. slower'speed: relative to engine: therewithshown. on ani enlarged scalefrom Fig. 1. speed',` Withtheqbladesf edili-1ste@v flora.higherpitchi Fig; Litis aview ot'apartlof thexshiftingrnenfiber angle;` InA otherA installationsitV maybe; desirable; and adj acentpartataken;orrthe plane. oilineli-d` toeperate the; propeller at ai lower speed; relative inFig; 3.; x

torengine: Speed-l during take-oft` than-"in crnisirigV 3Q Fig. 5ris1a..similarvie,w taken; on the planeotline Various reasons for utilizing such change :spi-'legil 5--5in.l'ig:.3.4

gearydrives'between theengineand,theproneller Fig. 6:.:is. a;viewfsimilar:toEig; 5r taken on the arefknown tofthe prior art.` and-do-notfinanywayi plane oflinee-Bsn Fign.,z;3.` affectthe-scoper'otthe invention.. Fig; 'Il isa viewsmiiarfto Figs.. 5\ andl taken `Ain object ofv this invention` is `toqorevidej imi- 35. onzthefplane' of line: 'le-1, in liigz;

movements in multi.-speeol` rednctiongear dri-Ves` Fig.: 8is'1 aviewsimlarzto"Figs.,5; and 6 tekenen...

for Vaircraftpropeilers\ whereby twoor more: thong the planeet. line 8:?8virrFig. 3; Sande horsepower may `loe transmitted` efflcieritl-yl Fig.' 9; is a view-,smilar-to'ligs. 5 andlataken: on

selected.l oneof at least-twondEerent-speedratios.. 40k. Fig. 10 is a longitudinal: sectional. View?A of; the which thevchange, fromV one speed ratioto an--i manually` operatedA shifting; valve.v for `hydraulically otheris eiectedby-powersmeans rapiqzlly{pos-it Wely` effecting the changes. in: thef .driving connections;

anadependably With-'minimum lossoa power; and for they propeller.

inwhich the shi-fting'mechanismlmay beremotel;7 Fig; 11?A is across-sectionat view); taken-` onl they controlled and is substantiallyvfoolproof... 45. p1ane=olinelle|l in Eig. 1,0,and11 Another Objectis to provide means; when shgiftl53gs.12 toY lfl.- aregenerallysimilar views. showing the drivingconnections between the engine, ing:k parts.v oftheshifting: mechanism( insuccesandpropeller shafts f-romone speedfratiototthefsiVely different operative positions.

012121812w t0' move en ,atllatr' 014 intermediate-mem- In tspreferrediorm, the inventionlmav'include ber: amember-fof the drivingaoonnections. thefollowna rnincipall parts.: First, agmain` driv-V 3 ing shaft such as the main crankshaft of an aircraft engine; second, a propeller shaft mounted coaxialy therewith; third, a driving member rotatable with said main driving shaft and having splines or teeth formed on its periphery fourth, a shiftable ring; member having teeth on its inner and outer peripheries and slidably movable over the teeth of the driving member; fifth, intermediate gears supported for rotation coaxially with said main shaft and having different numbers of gear teeth on their peripheries and having internal splines meshing selectively with the splines on the outer periphery of the shifting-ring member; sixth, a plurality of pinion carrying intermediate shafts arranged in a circular series about the main shaft and extending parallelly thereto, pinions on said shafts meshing with the above referred to intermediate driving gears; seventh, a driving pinion provided on each of said pinion shafts; eighth, a main driven gear keyed or splined directly to said propeller shaft and engaging said driving pinions; ninth, hydraulic meansfor actuating the speed changing mechanism,` to Amove said shifting ring member from one position to another; and tenth, means to reset the propeller governor while the change inl speed ratio is being effected. ,v Referring more in detail to the gwres of the drawings, there is shown a vSmall part only of a complete engine `crankoase I5 and the forward end only of the engine. crankshaft I2; This crankshaft I2 forms vthe main driving shaft for the propeller I4 of an airplane and is rotatably mounted in a front bearing E6 Within the casing I8. Coaxial with the crankshaft I2 and extending within a p-ortion thereof is the propeller shaft I8 having the propeller I4 (shown diagrammaticallyonly) secured to its forward end, the propeller shaft I8 being supported Within one ormore anti-friction bearings 26 suitably mounted Within a frame or housing 22 which may bev bolted to the crankcase. Ill and which may enclose the speed change4 device presently `to be described.

The propeller shaft I8 is also supported by having its engine `end extended within the forward end Iofthe main-shaft I2, suitable `bearings I8, 2l being provided therein to permit relative rotation of the two shafts.

. Mounted on the splined forward end of the 1crankshaft I2 is 4a drivingmember in the form of a thin sleeve 24 having internal. longitudinallyy extending splines 25 adjacent its .rear end engaging the splines 23 on the crankshaft, there being external splines 2l or teeth on the sleeve 24 adjacentv its forward end. .Engaging the external splines or teeth 27 at the forward. end of this sleeve 24 are internal splines 26 on the rear yof a ring member .26. This ring. member 26 is supported by means of a collar member 23 rotatably mounted on the propeller shaft-I8 forward of thev shaft I2. This ring .gear member 25 is, therefore, supported by the sleeve member 24 engaging its internal splines 29 and by the collar 28 rotatably supported by an intermediate cylindrical portion of the propeller shaft I8.l

On lthe propeller shaftY I8 at an intermediate portion is a large driven gear ill keyed or splined in fixed position thereon and having its teeth meshing with the teeth of a plurality of pinions 32 on the forward portions o-f short intermediate shafts 34 arranged in a circular series `about'the propeller shaft IS and rotatably mounted within suitable bearings provided therefor in the frame or housing 22. Y As shown in'lFig. l, each of the pinion shafts 34 is provided with three aligned bearings formed in the frame 22, the driving pinions 32 meshing with the gear 30 on the propeller shaft I8 being disposed between the forward and intermediate bearings. Pinions 36 and 38, which are of different :diameters for driving the shafts 34 at either of two speeds, are disposed between the intermediate and rear bearings. The pinions 36 and 38 are positioned adjacent each other on shaft 34 and are continuously in mesh with the intermediate ring gears and 42, respectively. As best shown in Fig. 3, gear 42 is rotatably supported ooncentrically of the crankshaft I2 on an annular flange 51 integral with an annular member 59 keyed to the sleeve 26. Gear 48 is rotatably mounted in a like manner on a ring 6I splined to the front end of sleeve 26.

To operatively connect one of these gears 40 or 4:2 drivngly to themain crankshaft I2, an axially slidable annular member 44 is provided having teeth or splines on its outer and also on its inner periphery. The teeth 43 on the outer periphery of the shifting' member 44 mesh selectively with corresponding teeth 45 and 41 on the inner periphery of one or the other of the intermediate or ring gears 4U or 42, depending upon the operative position to which the shifting ring member 44 has been moved. The teeth 49 formed on the in ner periphery of the ring member 44 engage at all times the elongated splines 5I on the outer surface of the driving member 26. With the yshifting member 44 in one ofy its operative positions, one speed reduction is effected between the crankshaft I2 and propeller shaft I8 by the gears 40, 36 and when the ring member 44 has been axially moved to its other operative position, another reduotion ratio is obtained by gears 42, 38.

Movement of this shifting member 44, in either direction is effected hydraulically, preferably by admission of fluid under pressure to one end or the'other of one or more cylinders 46 within which pistons 48 are reciprocable. Each piston 48 is provided at its intermediate portion with a plurality of rack teeth 59 each rack meshing with a small spur gear 52. Each of the small gears 52 is mounted adjacent its piston on a short rotatableshaft 54 supported Within the housing 22. On each of these shafts 54, at one end, is provided an eccentric or crank 56, `which engage at their outer or free ends within a peripheral groove formed in an anular actuating mem-ber 58. The actuating member 58 may be slidably mounted on a member 59 provided with axially extending slots (Fig. 7) so that the member 58 will be rotated with member 59, sleeve 26, and the engine shaft I2.

Each of the crank` pins 56 is surrounded by a bearing member or shoe 60 `directly engaging the side walls of the groove in the actuating member 58. In `one position of the pistons 48, the ring member 58 is in one extreme position 'and in the opposite position of the pistons 48, the eccentrics or cranks 56 have been rotated slightly more than one hundred and eighty degrees and have moved the ringr member 58 to its opposite extreme position. Fluid under pressure is admitted to correspending ends of the cylinders 46 Within which pistons 48 operate through appropriate conduits 91, |02 from a manually controlled valve 62 presently to be described. I Y

The annular member 44 'may be guided and supported asl shown upon the sleeve member 26 rotatable with` the main shaft and is resiliently connected to its shifting member 58 through springs 96. By means of this resilient connection,

theishittingf snembelr1 583m y-moveiiorifirone o'per-h atii'fepositionftaitsother extremefpositionbylitsl hydrauli'oT-aetuating means withoutbnecessi-tatin'g-` immediate obrresponding movement-of the ring# mecrrlbeiwlli.V

Referringfto Figss 31' et; sede, it* will Tbe'seenf that the ring member le hasfv outstanding;Vr laterallyV fornloneside,` a plural-ity ofir twoipfart bolts\=80. Tlevtmemberf tiff'isy sli'dable overt one* of the boltfsections v8!)E fandis' forcedresiliently in `one 'direction ortie other bymovement oflth'e actuating4 cra-nk Elli Supportedby'themembers;- 81,5 251inamanner--to permit sliding movement of the. shiftingfor ringf member Mi tov`-` its operative positions',` isfagateririg comprising two 'separatedfl'atannu`v` lar members -Sll and` 68l heidi spaced? apart a x'ed A distano@ by sle'evesf 10'# shown in- Fig. S'fdis'posed' betweenfthemembers iifa'nd iand heldinufiiced relation ztheretoby'bolts l2 eXtending-throughvtlie sleevest'lianditransversely through' the members Glandwl Alsltf is provided-Tin ringflE-tfor each boltfn arid Asleeveflflithuspermittinglmited-irelatii/ e' angularmovement between the gaterin'g an'd the'wsliifting member 4d.

Th'efrietional drivngmeans for the'intermedi ateY ringfgearsrl Iand iti.l and the members Arotatin'g with" vtldem comprisefclutoh'shoesfftfbest shown infFigi 9fin'sertedwithin recesses ir`1tlfieringfiifl` onone side of-ftbiefrinfrV member` Gli; When this "f inne-ri member f 66 andthe member Sli adjacent ttieretirotate faster than the gearV 4t2 the shoes 'Mflengage-a-flngeformed on the gear All' at one sideand` frietionally drive the-gear llilatthel samerA speed asA the inner member; The inner member' il-alwayslrotates at the same speed as the-engine=sliaft`- l'fllfor;` the'reason thatit is alwaysL directly" connected therewith; When the inner member 6I rotates slower'than thering geen Mlifriotio'nalmembers 'Ml-are disengaged and the gear'sMl andid?? driven by the propeller, slow down slightlyftdCorres'pond'to the speedfoflthel inner member driven-bythe engine.`

Etending from opposteside faces'of=the 'ring or-shiftingjmember Marepins` 'larranged infcon centricpircular series; When the ringm-ember Misiin one for the otherfof its operative positions; irl-'which -it?drives-one or `the other of -fth'e gears"A lili-4125, the pins'ltonl one-side eng-agecorrespond'- ing openings I`withinthe annular members 6$-or fof-thgatering, whioh'is driven through bolts 12'! 'and` "sleeve :lllfbyf shifting member- LM.- When the=member Mds-in midpositionthe gears Lte; 421areiffree-to rotate withthe propeller I4 by their ownlmomentum; or are friotionally drivenby-ffrictio'n" shoes v'Hlwhenever thespeed of sleeve- ZGfexoeeds the speed fof gear 40:

llflileL the ring shifting member'fid'is f inl its centralfrf neutral i position, the` propeller* shaft Ifiis-fnotfbeingpositively driven and during this period" thef-frietional drive: provided b'y `clutch shoes T4lprevent`s.overspeeding of the engineand hel-ps to synchronize the-speeds'- of gear M11A and shiftingifring 44:11 As described below, the pin 1B outstanding fromth'e; shifting member Mllbeoomev aligned openings provided for `them inethe rotating fgate'J members for.` 69 only when the speedofthefshifting member lli-s approximatelyf equal to-` thespeed-"off `the corresponding gear dal orr42f`se-tliat theshifting member Alimay then*- movei irito^ itsextreme-L oroperative position smoethlyand with va` snap action'to `provide a' posi-'- tiveegearffdz'vebetween the engine and propeller shaftsfZarid-l8,\`respectively= f V the gate ring'a'formed bnr-members: Staandziwarew twowpartbolts eachforL'Whicneomprise: t'wo'zprim i i cipalwfelongated membersvsg si.: The' Shanks" of' eaehoftheboltim'einbersiDfextendfreelyrthrough 5 holes providedintheactuating membervtai These belt members-Sd passing throughthe actuating mem-ben sehaveinutsfzfthreaded onvtneiiv` ends and onflth'eiriopposit'e ends areeachprovidedwith1 anntegral heards'll-L Tlescopieally:dispos'edlrela; i tive :to2 Idieserbolt-rmembers an: fonmovement feoaxially rtherewitit are sleeveb'olt .members a Iv havingint'e'grailyxformed heads 86 at '1 one end and attehedzl-heads 8181i ati. their opposite 1 ends. Portions ofi'th'e-i peripheryiof/these sleeve boltlmemi bers 8l@ are out1-away""torL formlslotspermittingmovemehtiofithe* headstl forn'ledv ori the* inner boltf membersl 8015l The actuating f member" 5B is dispesedlbetweenrtheintegrar-head eofithe sleeve boltfmember 81 l aridlth'eA nuts- 82 "on rthe inner bolt member? *Between -the'vintegral-iheads 3ft an'd i offithei two `Abolt?members and surrounding. the :in-V termediateportionsofitheboltsfareidisposedcoin pressed co'il fsp'rings SB if'oreingt` the head'sf apart aslftrf'ayp''errittedlibythe'assemblyV l Between'the'f attached heads 83% ofthe sleev members'l and* the integralllheads lfofthev inner bolt-members fliisetheshifting member 46,1 the operation; oil Wliicliwill presently be more fullylfd'esoribed: It? isA byresilient movement" of" directionfdtofthe right'as'see-n in'Fi'g. 3) byitsV4 previously. describedrfhydraulic "mechanism" pulls` the inner bolt'member f to" cthe f' rightfand com'- pre's s i-the lcoil' springs" I tilt-disposedl between the head `BilliaritiJ86; Tl'iis`-fpressurefof the springs-Sii winba Veenertedfinf@ a directronr to resilientiy force thersleeve lboltimerriber'1131 tofthre right whichwillv alol force 'thet ringff member` M toward its"` rightI-` E, gatefring Betweenthe* gears All? and- 423 is'a" By v`reference to Fiess 12-'et1 seq., the sequen'cefof operation off" the shifting mechanism' for'the member '44 willrlb'eclea'r: Fig; 12 sho-wsithefshift;

ing member 44, positioned for the lowerspeed- 051i ratio fr the propeller. When theY actuator member `5'34Y'is1 =-movedl tofthe right from the position is'ftocompress-thespririgs 90'between the heads on` theetwo boltmembersffand 8l `asshown infFig. 70,A 1313- The rstllpartof the 'movement 'of member 5pairtiallyfcompresses springs 190 lloutdis'engagement i of!l rriemberi 441 islfnot accomplished' untilf abtuatorim'ember 258E continuesl fronti-the position shown Sir-rf Figi l3l toit e1-'position-shownlirf-Fig; l4 14e Atithis timefthesprings 90= arefsolrdlj'sbacked this shifting member 44 by member 5S that-the or compressed between the members 84 and 86 thus Icreating a positive pull on the bolt members 8| land shifting ring 44 by pistons 49. To facilitate release of the spline connection between shifting member 44l and gear 40, the throttle may be manually operated to at least momentarily release the load being transmitted .through these splines, enabling the energy previously stored up by compression of springs 90 to quickly disengage the shifting member from the low speed gear 44 and move it to the neutral or non-driving position shown in Fig. 14, which also permits the actuating ring 58 to move to its extreme right hand position. Furtherv movement of the shifting ring 44 is prevented, however, because the right hand set of the pins 18 and their corresponding holes are misaligned with respect to the left hand set of pins 18 and their corresponding holes as shown in Fig. 3 and Fig. 14, and consequently the pins 18 strike against portions of the right hand member 68 of the gate ring, preventing immediate engagement of the teeth on member 44 with the splines on gear 42. As the gear 42 is rotating slower than gear 49 at the moment the member 44 is disengaged from gear 40, this misalignment of the two sets of pins and holes prevents clashingor breakage that would otherwise result from an attempt to positively lock together the engine and propeller masses with parts rotating at dierent speeds.

In the neutral position shown in Fig. 14 the springs 90 still urge the shifting member 44 to the right, causing pins 18 to press member 68 against the inner ilange on gear 42, thus creating a frictional drag which tends to cause member 68 to rotate at the speed of gear 42. Thus as long as gear 42 is rotating slower than shifting member 44 the sleeve 10 of the gate ring will be held against that side of the slot in member 44 in which the right hand set of pins 18 are not aligned with the holes in gate member 68. But as the speed of the engine is reduced the sleeves will be dragged over against the other side of the slots in shifting member 44 at the instant the speeds of the shifting member and the gear 42 cross and when this occurs the right hand set of pins 18 become aligned with the holes in gate member 68 and springs 90 cause the shifting member to instantly snap into its high speed driving position, as shown in Fig. 15. In actual practice the shift is made very rapidly, merely by opening a valve to admit actuating fluid to the cylinders 46 and then manually varying the throttle position one or more times. The Yshifting mechanism then acts rst to disengage the low speed gear and then tosnap the shifting member into the high speed position atV the instant its speed becomes synchronizedwith the speed of high speed gear 42. The shifting member 44 remains momentarily only in its neutral or nondriving position and is then moved to its new operative position with a snap action, The propeller will then be positively driven at its higher speed ratio. j

Fig. 16 shows the reverse operation of the change speed mechanism in which the actuating member 58 has been returned to its mid-position by lpistons 48 to again com-press the springs 90 and resiliently force the member 44 toward the left.

Fig. 17 shows the actuating member 58 after having moved to its extreme left hand position and with the shifting member moved-to its mid or inoperative position. From the position shown in Fig. 17, the shifting member. 44 is moved to its left hand position as shownin Fig. 12 as soon as the openings in plate 69 are aligned with the pins 18, in a manner similar to that described above. In the shift from high to low, the engine speed is increased relative to propeller speed when the shift is made. Clutch elements 14l are particularly important during this process to :prevent over- -speeding of the engine.

At the time the shift from low to high speed is effected it may be desirable to also reset the propeller I4 to a different speed. For kthis purpose movement of the lower piston 48 to move the actuating member 58 from its low to its high speed position uncovers port 92 in the lower cylinder 46 so that when the pistons 48 have moved a portion of their travel yand the shifting member 44 is about to be moved to its ycentral or neutral position, fluid under pressure is admitted from line |82 through line 92 to valve 94.

To open the valve 94 at the proper time to admit fluid under pressure to the governor by conduit 96, rollers 98 are provided on spring pressed plungers which urge ring 63 to the left, the lower plunger 94 being also formed as a valve as shown in Fig. 1. When shifting member 44 snaps into its high speed position, the righthand set of pins 18 contact correspondingly spaced buttons 65 on ring 63 and force the ring 63 and rollers 98 to the right, causing valve 94 to admit pressure fluid from line 92 into line 96 leading to the governor reset mechanism. In the lowerI speed ratio position of Fig. 1, valve 94 is held in the position shown in which line 96 is opened to drain. Thus the propeller governor is reset by valve 94 to either higher or lower speed settings as the shift is made, in a manner more fully explained in United States Patent No. 2,365,204, granted December 19, 1944, to Erle Martin et al., assigned to applicants assignee.

The manual c-ontrol valve 82 for initiating operation of the shifting mechanism may be located on the housing 22 and actuated by a lever |00 and control rod (not shown) extending to the cockpit of the airplane. Normally, iluid under pressure (such as engine oil) may be supplied constantly to one end of each of the cylinders 46 as by conduits 91 so that the actuating member 58 will be held in its left hand position and connections will be maintained for the lower speed ratio of the propeller. Figs. 10 and 11 show the valve t2 in the position in which oil under pressure is admitted through conduit 61 to a circumferential groove in valve 62, to a longitudinal groove |0| and thence to conduit 91. This actuates the pistons'48 to the -position shown in Fig. 2. In this position of valve 62 conduit |02Vis open'to the drain |53 to permit iluid to exhaust from the opposite ends of cylinders 46. By rotating valve 62 to admit fluid under pressure to conduits |02 shown in Fig. 2 and simultaneously open the conduits 91 to drain |03, the pistons 48 will be moved to the opposite ends of their cylinders and will change the speed ratio as above described. This control of the iluid to move the actuating member 58 may be effected entirely by manual operating of the valve 62 from the cockpit.

A spring pressed plunger |05 is mounted in the casing for valve 62 so that it normally engages one of the longitudinal grooves in the valve and prevents rotation of valve when the engine is not running and no pressure exists in conduit 61. With-pressure in conduit 81 and circumferential groove 95 fluid under pressure vwill be admitted to the valve end of the cylinder within which the plunger |05 operates. For this purpose a small conduit |01 is provided. This pressure serves to 9 retract the Lplunger y:HiB/and `permitrotation of the .valve 62. The oppositecnd of the cylinder It ui-swt'o .be understood .thatthe invention. is. not

:.limtedto the specific .embodiment herein illusftratedran'd .described, but .may Abe used. in fother =zwways fwithout departure from :the spirit of A'the invention as de'nedbythe following claims.

I claim:

1. A two-speed drive for aircraft propellers comprising in combination, an engine shaft mounted for rotation within an engine frame, a sleeve secured thereto, gears mounted on said sleeve concentric with said shaft, a plurality of shafts mounted in said engine frame and each having pinions thereon respectively engaging said gears, a propeller shaft concentric with said engine shaft, driving connections between said pinion carrying shafts and said propeller shaft, a ring member slidably mounted within said gears for drivingly connecting either of said gears with said sleeve, a crank member for moving said ring member into driving engagement with one or the other of said gears, and hydraulic means to actuate said crank member.

2. A two speed drive for aircraft propellers comprising in combination, an engine shaft mounted for rotation within an engine frame, a sleeve secured thereto, gears mounted for rotation relative to said sleeve concentric with said shaft, a plurality of shafts mounted in said engine frame and each having pinions thereon respectively engaging said gears, a propeller shaft concentric with said engine shaft, driving connections between said pinion carrying shafts and said propeller shaft, a ring member slidably mounted within said gears for drivingly connecting either of said gears with said sleeve, a crank member for moving said ring member into driving engagement with one or the other of said gears, and means to actuate said crank member approximately one half a revolution to move said ring member from one operative position to the other.

3. A two speed drive for aircraft propellers comprising in combination, an engine shaft mounted for rotation within an engine frame, a sleeve secured thereto, gears mounted von said sleeve concentric with said shaft, a plurality of shafts mounted in said engine frame and each having pinions thereon respectively engaging said gears, a propeller shaft concentric with said engine shaft, driving connections between said pinion carrying shafts and said propeller shaft, a ring member slidably mounted within said gears to limiting positions in either direction to form inter-connecting means between one of said gears and said sleeve in either position, and means for moving said ring member to its opposite limiting positions.

4. A two speed drive for aircraft propellers comprising in combination, an engine shaft mounted for rotation within an engine frame, a sleeve secured thereto, gears mounted on said sleeve concentric with said shaft, a plurality of shafts mounted in said engine frame and each having pinions thereon respectively engaging said gears, a propeller shaft concentric with said engine shaft, driving connections between said pinion carrying shafts and said propeller shaft, a ring member slidably mounted within said gears Ail() -:ar'1d14 forming interconnecting .means respectively ib'etween'feach'fof'saidfgears l-and isleeve, E'a 'cran-k member forfmoving:saidzmemberrintodrivng; en-

gagement AQwithfon'e` for fthe fother `of'said "gears,

afpistcn icon-nested :to lsaid 1 crank immber, and "hydrauli'c'frrieans to factuate said piston` to'rotate "saidicrankmemberitooppositeipcsitions.

115. A itwoaspeed reduction :drive iforfiaircraft propellers comprising :2in '.l'combinati'on, '1ra' drive shaft,fa'propellershaftkflriventhereby, gear connections between said drive and propeller shafts, a shifting member-infsaidconnections movable to `twol alternately operative positions, an-actuator for said shifting member, saideactuator 4having first andsecond operative positions, a hydraulic piston movable within a cylinder to effect shifting movements of said actuating member from one to the other of said positions, a port overrun by said piston during movement in one direction, and means to supply fluid under pressure through said port to a propeller speed governor resetting valve operatively associated with said shifting member.

6. In a change speed drive for an aircraft propeller having `a speed governor, a driving shaft, a pair of alternatively usable gears, a shifting member selectively engaging one or the other of said gears to drivingly connect one of said connected gears to drive said propeller from said shaft, actuating means for moving said shifting member to either position, means for preventing engagement of said shifting member with said gears except when their speeds are approximately equal, pressure means to effect movement of said shifting member, and valve means operated by movement of said actuating means to admit uid under pressure to the propeller speed governor during movement of said slidable member.

7. In a change speed drive for an aircraft pro` peller having a speed governor, a driving shaft, a pair of alternatively usable gears for driving said propeller from said shaft in different gear ratios, a shifting member for selectively engaging one or the other of said gears with said driving shaft, a propeller speed governor resetting valve, and an actuating member having first and second operative positions effective upon movement from one to the other of said operative positions to operate said valve and move said shifting member out of engagement with one of said gears and into engagement with the other of said gears. 8. In a change speed drive for an aircraft propeller having a speed governor, a driving shaft, a pair of alternatively usable gears for driving said propeller from said shaft in different gear ratios, a shifting member for selectively engaging one or the other of said gears with said driving shaft, a propeller speed governor resetting valve, an actuating member resiliently connected to said shifting member and having first and second operative positions effective upon movement from one to the other of said positions to move said shifting member out of engagement with one of said gears and into engagement with the other of said gears, and means actuated by said shifting member for operating said valve. l

9. In a change speed drive for an aircraft propeller having a speed governor, a driving shaft, a pair of alternatively usable gears for driving said propeller from said shaft in different gear ratios, a shifting member for selectively engaging one or the other of said gears with said driving shaft, a propeller speed governor resetting valve, an actuating member having first and second operative positions effective upon movement REFERENCES CITED The following references are of record in the le of this patent:

Number 12 UNITED STATES PATENTS Name Date Chalmers Dec. 10, 1912 Ahlm July 16, 1929 Kohler Feb. 21, 1933 Wahlberg Nov. 21, 1933 Peterson et al Mar. 1'7, 1942 Peterson et a1 Oct. 24, 1944 Peterson et al Apr, 2, 1946 Brownyer Apr. 16 1946 Price June 18, 1946 

